public class Sort {
    //1.直接插入排序
    public static void insertSort(int[] array) {
        for (int i = 1; i < array.length; i++) {
            int temp = array[i];
            int j = i - 1;
            for (; j >= 0; j--) {
                if (array[j] > temp) {
                    array[j + 1] = array[j];
                } else {
                    break;
                }
            }
            array[j + 1] = temp;
        }
    }

    //2.希尔排序
    public static void shellSort(int[] array) {
        int gap = array.length / 2;
        while (gap > 0) {
            for (int i = gap; i < array.length; i++) {
                int temp = array[i];
                int j = i - gap;
                for (; j >= 0; j -= gap) {
                    if (array[j] > temp) {
                        array[j + gap] = array[j];
                    } else {
                        break;
                    }
                }
                array[j + gap] = temp;
            }
            gap /= 2;
        }
    }

    //3.选择排序
    public static void selectSort(int[] array) {
        for (int i = 0; i < array.length; i++) {
            int minIndex = i;
            for (int j = i + 1; j < array.length; j++) {
                if (array[j] < array[minIndex]) {
                    minIndex = j;
                }
            }
            swap(array,minIndex,i);
        }
    }

    private static void swap(int[] array, int j, int i) {
        int temp = array[j];
        array[j] = array[i];
        array[i] = temp;
    }

    //4.冒泡排序
    public static void bubbleSort(int[] array) {
        for (int i = 0; i < array.length; i++) {
            boolean flag = false;
            for (int j = 0; j < array.length-1-i; j++) {
                if (array[j] > array[j+1]) {
                    swap(array,j,j+1);
                    flag = true;
                }
            }
            if (flag == false) {
                break;
            }
        }
    }
    //5.堆排序
    public static void heapSort(int[] array) {
        creatBigHeap(array);
        int end = array.length - 1;
        while (end > 0) {
            swap(array, 0, end);
            shiftDown(array,0, end);
            end--;
        }
    }

    private static void creatBigHeap(int[] array) {
        for (int i = (array.length-1-1) / 2; i >= 0; i--) {
            shiftDown(array,i,array.length);
        }
    }

    private static void shiftDown(int[] array, int parent, int end) {
        int child = 2*parent + 1;
        while (child < end) {
            if (child+1 < end && array[child] < array[child+1]) {
                child++;
            }
            if (array[child] > array[parent]) {
                swap(array,child,parent);
                parent = child;
                child = 2*parent + 1;
            } else {
                break;
            }

        }
    }

    //6.快速排序
    public static void quickSort(int[] array) {
        quick(array,0,array.length-1);
    }

    private static void quick(int[] array, int begin, int end) {
        if (begin >= end) {
            return;
        }
        int pivot = parttion(array,begin,end);
        quick(array,begin,pivot-1);
        quick(array,pivot+1,end);
    }

    private static int parttion(int[] array, int begin, int end) {
        int left = begin;
        int right = end;
        //此处可以采取三数去中
        int pivot = array[begin];
        while (left < right) {
            while (left < right && array[right] > pivot) {
                right--;
            }
            array[left] = array[right];
            while (left < right && array[left] < pivot) {
                left++;
            }
            array[right] = array[left];
        }
        array[begin] = pivot;
        return left;
    }

    //7. 归并排序
    public static void mergeSort(int[] array) {
        mergeSortFuc(array,0,array.length-1);
    }

    private static void mergeSortFuc(int[] array, int left, int right) {
        if (left >= right) {
            return;
        }
        int mid = (left + right) / 2;
        mergeSortFuc(array, left, mid);
        mergeSortFuc(array, mid + 1, right);
        merge(array,left,mid,right);
    }

    private static void merge(int[] array, int left, int mid, int right) {
        int s1 = left;
        int s2 = mid + 1;
        int e1 = mid;
        int e2 = right;
        int[] temp = new int[right - left + 1];
        int k = 0;
        while (s1 <= mid && s2 <= right) {
            if (array[s1] < array[s2]) {
                temp[k++] = array[s1++];
            } else {
                temp[k++] = array[s2++];
            }
        }
        while (s1 <= mid) {
            temp[k++] = array[s1++];
        }
        while (s2 <= right) {
            temp[k++] = array[s2++];
        }
        for (int i = 0; i < k; i++) {
            array[left + i] = temp[i];
        }
    }
}
